A few algebra questions

A biathlon event involves running and cycling. I can cycle 30km/h faster than I run. I spend 48 minutes running and a third as much time again cycling in an event. The event covers a total distance of 60km. How fast do I run?

A real estate agent sells 22 houses in six months. He makes a commission of $11,500 per house on some and $13000 per house on remainder. If his total commission over the six months was $272,500, on how many houses did he make a commission of $11,500?